Andrew Ian Levin

Recurrence of cardiotoxicity after lipid rescue from bupivacaine-induced cardiac arrest

Accidental intravascular administration of bupivacaine during performance of a brachial block precipitated convulsions followed by asystole. The patient was rapidly resuscitated using cardiopulmonary resuscitation, supplemented by 150 mL of 20% lipid emulsion. Nonetheless, cardiac toxicity reappeared 40 min after completion of the lipid emulsion. In the absence of further lipid emulsion, amiodarone and inotropic support were used to treat cardiotoxicity. This case suggests that local anesthetic systemic toxicity may recur after initial lipid rescue. Since recurrence of toxicity may necessitate administration of additional doses of lipid emulsion, a sufficient quantity of lipid emulsion should be available when regional anesthesia is performed.

Arterial oxygenation and one-lung anesthesia.

Purpose of review In the presence of the obligatory shunt during one-lung ventilation, arterial oxygenation is determined by the magnitude of the shunt in addition to the oxygen content of the mixed venous blood coursing through that shunt. The present discussion aims to heighten awareness of factors determining arterial oxygenation during one-lung anesthesia, other than the magnitude of the shunt and dependent lung low-ventilation perfusion units. Recent findings A convenient way to increase mixed venous and thereby arterial oxygenation is to raise cardiac output. While this approach has achieved some success when increasing cardiac output from low levels, other studies have highlighted limitations of this approach when cardiac output attains very high levels. The effect of anesthesia techniques on the relationship between oxygen consumption and cardiac output could also explain unanswered questions regarding the pathophysiology of arterial oxygenation during one-lung anesthesia. Summary The effects of anesthesia techniques on oxygen consumption, cardiac output and therefore mixed venous oxygenation can significantly affect arterial oxygenation during one-lung anesthesia. While pursuing increases in cardiac output may, under limited circumstances, benefit arterial oxygenation during one-lung ventilation, this approach is not a panacea and does not obviate the necessity to optimize dependent lung volume.

Arterial oxygenation during one-lung anesthesia.

S zegedi et al. (1) studied the effects of normovolemic acute hemodilution on arterial oxygenation in supine subjects during one-lung anesthesia (OLA). After hemodilution, patients who had chronic obstructive airways disease (COAD) exhibited decreases in Pao2, whereas there were no changes in subjects with normal lungs, nor in a control group with COAD who did not undergo hemodilution. The effects of hemodilution during OLA have not been previously described, and the reasons for their findings are not obvious. Intuitively, one may suspect that hemodilution increased pulmonary shunting in the COAD group. There are however, a number of factors influencing arterial oxygenation during OLA that need to be considered (2). These factors may be introduced by considering the shunt equation:

Heparinase Thromboelastography Compared With Activated Coagulation Time for Protamine Titration After Cardiopulmonary Bypass

OBJECTIVE The present study is a comparison of two point-of-care (POC) tests as endpoints of protamine titration after CPB. The authors hypothesized that using the heparinase-kaolin thromboelastography (TEG-HK) R-time difference would more readily identify residual heparin necessitating additional protamine than when using activated coagulation time (ACT). The primary endpoint was the between-group difference in protamine dose. Whether this approach would lessen postoperative bleeding and sequelae also was investigated. DESIGN Single center, blinded, prospective, randomized study. SETTING University teaching hospital. PARTICIPANTS Eighty-two adult patients for on-pump coronary artery bypass and/or valve surgery. INTERVENTIONS Patients were randomized. In the ACT group, protamine was titrated until ACT did not exceed baseline by more than 10%. In the TEG group, a TEG-HK R-time difference less than 20% was targeted. Protamine was repeated to achieve the endpoints. Clinicians in the ACT group were blinded to TEG data and vice versa. MEASUREMENTS AND MAIN RESULTS There was no between-group difference in total protamine dose (3.9 ± 0.6 and 4.2 ± 0.7; 95% CI of the difference between means: -0.544 to 0.008 mg/kg; p = 0.057) or protamine:heparin ratios (1.3:1 and 1.4:1; 95% CI of the difference between means: -0.05 to 0.03 mg/mg; p = 0.653). In the ACT group, 17% of patients required a second protamine dose, and in the TEG group, 24% of patients required a second protamine dose. No between-group differences in the postoperative transfusion requirements or intensive care unit length of stay were demonstrated. CONCLUSION No difference was identified in protamine dosing using either ACT or TEG-HK R-time difference as endpoints. Heparinase TEG may be useful for monitoring heparin reversal.

Lipid rescue: the use of lipid emulsions to treat local anaesthetic toxicity

ABSTRACT Despite increasing safety of regional anaesthesia, the growth in the popularity therof implies that local anaesthetic toxicity will occur occasionally. Local anaesthetic cardiotoxicity, even when using “safer” modern local anaesthetics, is notoriously resistant to standard resuscitation. The aim of this paper is to review current knowledge regarding the use of lipid emulsions to treat local anaesthetic toxicity.

Tension Pneumopericardium During Positive-Pressure Ventilation Leading to Cardiac Arrest

m HE EXISTENCE OF a communication between the respiratory tract and the pericardial sac can lead to the develpment of a pneumopericardium.1,2 Although the resultant neumopericardium commonly has clinically insignificant conequences during spontaneous respiration, initiation of interittent positive-pressure ventilation (IPPV) in the presence of uch a communication can cause a tension pneumopericardium o develop.1,3,4 If a clinically insignificant pneumopericardium s diagnosed before initiation of or during IPPV, a high index f suspicion should be maintained for the development of a ubsequent tension pneumopericardium.

Transcardiopulmonary Thermodilution-Calibrated Arterial Waveform Analysis: A Primer for Anesthesiologists and Intensivists

From the Department of Anesthesiology and Critical Care, University of Stellenbosch, Tygerberg Hospital, Cape Town, South Africa. Address reprint requests to Andrew Levin, MBChB, DA, MMed (Anes), FCA, PhD, Department of Anesthesiology and Critical Care, University of Stellenbosch and Tygerberg Hospital, Room 2044, Clinical Building, Cape Town, Western Cape 7505, South Africa. E-mail: ail@sun.ac.za

Labour epidural analgesia audit in a tertiary state hospital in South Africa

Background: Neuraxial analgesia is currently considered to be the most effective method of intrapartum analgesia, causing little maternal and foetal sedation. While epidural analgesia has been well studied in developed countries, it is uncertain whether or not the results, particularly regarding complication rates, can be extrapolated to the South African public hospital context.Method: The available records for indications, complications and patient satisfaction of parturients receiving labour epidural analgesia at Tygerberg Hospital from 1 January to 31 December 2012 were reviewed in a retrospective one-year audit.Results: During the audited period, 157 (2.2%) of 7 005 parturients managed for labour and delivery at our hospital received epidural analgesia. One hundred and forty-nine records could be retrieved for analysis. Epidural analgesia was only used for medical indications and not patient demand. 73.2% of indications were cardiovascular disease and morbid obesity. Excluding a 13.4% incidence of hy...Background: Neuraxial analgesia is currently considered to be the most effective method of intrapartum analgesia, causing little maternal and foetal sedation. While epidural analgesia has been well studied in developed countries, it is uncertain whether or not the results, particularly regarding complication rates, can be extrapolated to the South African public hospital context. Method: The available records for indications, complications and patient satisfaction of parturients receiving labour epidural analgesia at Tygerberg Hospital from 1 January to 31 December 2012 were reviewed in a retrospective one-year audit. Results: During the audited period, 157 (2.2%) of 7 005 parturients managed for labour and delivery at our hospital received epidural analgesia. One hundred and forty-nine records could be retrieved for analysis. Epidural analgesia was only used for medical indications and not patient demand. 73.2% of indications were cardiovascular disease and morbid obesity. Excluding a 13.4% incidence of hypotension, a 15.4% incidence of early complications [the majority (91.3%) being minor in nature] was observed. One (0.7%) potentially fatal incident of accidental systemic local anaesthetic administration and toxicity with cardiac arrest occurred. Parturients reported being “happy” or “very happy” (50% and 36%, respectively) with the epidural analgesia. Conclusion: Only 2.2% of parturients received labour epidural analgesia at a tertiary “developing world” hospital, primarily because of personnel constraints. Indications were predominantly cardiovascular disease and morbid obesity. Analgesia on demand was not provided. However, the incidence of complications from labour epidural analgesia was in keeping with that observed in developed countries. Most women were “happy” with their labour epidural analgesia.

Lipid emulsion therapy: non-nutritive uses of lipid emulsions in anaesthesia and intensive care

Lipid emulsions were introduced into clinical practice more than five decades ago as a calorically dense, non-glucose-based energy source for parenteral nutrition. Recently, intravenous lipid emulsions have been used as rescue for systemic local anaesthetic toxicity. However, the non-nutritive, therapeutic roles of lipid emulsions have recently expanded. This review considers these newer uses of lipid emulsions as drug administration vehicles, for treatment of lipophilic drug toxicity, and as modifiers of ischaemia-reperfusion injury in the anaesthetic and critical care environments. The potential adverse effects of lipid emulsion administration are also succinctly addressed.

Expediting red blood cell transfusions by syringing causes significant hemolysis

Techniques commonly used to expedite blood transfusions include pneumatically pressurizing red blood cell (RBC) bags or manual syringing its contents. We compared these techniques on RBC hemolysis using a simulated transfusion model.